Pickup trucks are motor vehicles with a front passenger area, often referred to as a cab, and an open top rear cargo area, often referred to as a box. The box typically has a substantially flat bed from which two sidewalls and a forward interconnecting headboard extend upwardly therefrom. Pickup trucks may also employ a bottom hinged door, commonly referred to as a tailgate, hinged at the rear edge of the bed and closable to provide a fourth wall for the cargo area. Cabs and boxes may be separate assemblies or part of the same unibody structure. Pickup trucks are popular largely because the box allows them to be utilized in so many different ways, including carrying a variety of types of cargo and towing various types of trailers.
Traditionally the majority of body structures on pickup trucks have been formed from steel alloys. Through years of experience, pickup truck designers have learned how to engineer steel truck body parts that withstand the variety of demanding pickup truck applications. The current regulatory and economic environments have increased the importance of making pickup trucks more fuel efficient as well as functional and durable. One way to reduce the fuel consumption of a vehicle is to reduce vehicle structure weight.
Aluminum alloys typically have a higher strength to weight ratio than steel alloys. Consequently, replacing steel with aluminum offers the potential for weight reduction. However, the elastic modulus of aluminum is generally lower than the elastic modulus of steel. As well, fabrication techniques and methods of joining parts that work well for steel parts may not work well for the same aluminum part. Due to these and other differences, simple material substitution does not necessarily produce an acceptable design.
Oil canning is a phenomenon that may occur when light-gauge metal is used in flat structures. Internal stresses in the metal may cause the material to bulge inwardly or outwardly in localized areas and oscillate back and forth. These bulges/oscillations may be visible, especially under certain lighting conditions. Furthermore, a transition from an inward bulge to an outward bulge, or vice versa, may produce a popping sound. Oil canning may be more prevalent in aluminum structures than steel structures of the similar shapes and sizes. Although oil canning does not alter objective measures of structural integrity, it may be perceived by consumers as an indication of lower quality.
Manufacturers of pickup trucks often like to place an emblem or badge on an external tailgate panel to provide information as to the make or model of the pickup truck. The emblems have a shape and weight and may increase the opportunity for oil canning when placed on a flat structure. The emblem may also extend outwardly from the surface of the metal also increasing an opportunity for oil canning. As well, other components, such as lights or cameras, may be included as part of the emblem structure adding even more weight and complexity to the emblem and a yet even greater potential for the oil canning phenomenon.